WASHINGTON - In a speech harshly critical of Israel, U.S. Secretary of State John Kerry warned on Saturday that current trends in the Israeli-Palestinian conflict are leading to a one-state reality.

Addressing the Saban Forum in Washington, D.C., Kerry also warned of the Palestinian Authority's collapse and called on Prime Minister Benjamin Netanyahu to prove that his support for the two-state solution isn't just a slogan but a part of Israeli policy.

The secretary of state made the remarks a week after visiting Jerusalem and Ramallah, a trip during which he failed to secure willingness on the part of Netanyahu and Palestinian President Mahmoud Abbas to take confidence-building measures. Kerry admitted to feeling frustration vis-à-vis the process in a brief interview with former U.S. special envoy for Middle East peace Martin Indyk, who now serves as vice president of the Brookings Institute, which organizes the Saban Forum.

Kerry made clear in his speech that the U.S. remains committed to the two-state solution, but asserted that the two sides are the ones who must take decisions that affect their future.

The secretary of state noted that despite Netanyahu's expression of support for the establishment of a Palestinian state, several Israeli cabinet ministers have declared their opposition to the move.

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Kerry said that if the current situation continues, it is unclear how long the Palestinian Authority can survive.

"If there is a risk the Palestinian Authority might collapse and Israel wants it to survive, shouldn't Israel do more to help sustain it?" Kerry said.

"Without the Palestinian Authority, Israel will be responsible for civil administration of the West Bank - it costs billions," Kerry said. "Without the Palestinian Authority’s security forces, the IDF would be forced to deploy tens of thousands of soldiers to the West Bank indefinitely."

Kerry said that the distrust between the two sides has never been more profound. "President Abbas feels great despair - more than I have ever heard him," he added.

"I believe that many people in the security establishment in Israel want to see steps for strengthening the Palestinian Authority," the secretary of state said.

Kerry criticized Israeli settlement construction, saying that it raises questions about Israel's long term intentions. Kerry noted that Palestinians didn’t receive any construction permits in Area C in 2015.

'One-state solution is no solution'

The secretary of state said that the two-state solution for the Israeli-Palestinian conflict mustn't become a "slogan," but warned that "current trends are leading for a one-state reality."

"We have to be honest about what a one-state solution looks like," Kerry said, warning that in such a case Israel couldn't maintain its character as Jewish and democratic, asking rhetorically what the international reaction would be to such a scenario, and saying that true peace with its neighbors will not be possible under such conditions.

"The one-state solution is no solution at all for a Jewish, democratic Israel living in peace," he warned.

Saying that peace is the best way to achieve security, Kerry stated that first of all, the violence must stop. "There's no justification for violence against civilians. Israel has the right and the obligation to defend itself."

"We need people to act in restraint. The Palestinian leadership should stop the incitement and condemn terror attacks," he said.

On Friday, Defense Minister Moshe Ya'alon addressed the Forum and said that he opposed the one-state solution, stating that Israel did not want to govern the Palestinians. "We are happy they already have their political independence," he said, adding that Israel wants to strengthen Palestinian competence to govern themselves.

Earlier on Saturday, Yesh Atid chairman Yair Lapid addressed the Forum, saying that solving the conflict "is not the number one priority of Israel - it is the only priority." Saying that Israel must move toward solving the conflict as soon as possible, Lapid said: "We have been waiting for 40 years for the right timing to have peace with the Palestinians. Enough is enough - we need to do it."

"We want a transition to a unified non-sectarian Syria," Kerry said, adding that the U.S. isn't nave about the diplomatic effort in Syria. "It's difficult," he admitted. However, he added that the Vienna talks were "the most promising diplomatic effort regarding Syria in the last years."

Regarding the nuclear deal with Iran, Kerry addressed Israel directly, saying that he knows Israel still has concerns, but that the U.S. is "convinced that we will know what Iran is doing."

"Under the nuclear deal all of Iran's pathways to a bomb are blocked," he said, adding that it was the deal was the right thing to do, "regardless of whether they will change their behavior or not."

Haaretz.com, the online edition of Haaretz Newspaper in Israel, and analysis from Israel and the Middle East. Haaretz.com provides extensive and in-depth coverage of Israel, the Jewish World and the Middle East, including defense, diplomacy, the Arab-Israeli conflict, the peace process, Israeli politics, Jerusalem affairs, international relations, Iran, Iraq, Syria, Lebanon, the Palestinian Authority, the West Bank and the Gaza Strip, the Israeli business world and Jewish life in Israel and the Diaspora.